<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width,initial-scale=1.0">
  <title>Document</title>
  <style>
    .wrapper {
      height: 400px;
      border: 6px dashed red;
      /* filter: blur(0px); */
    }
    .wrapper-inner {
      position: fixed;
      background-color: cornflowerblue;
      width: 300px;
      top: 0px;
      bottom: 0px;
    }
  </style>
</head>
<body>
  <div class="wrapper">
    
    wrapper
    <div class="wrapper-inner">test</div>

  </div>
</body>
</html>